As a result of the letter, MG&E plans to keep operating the power plant beyond 2011 -- but using natural gas rather than coal as the fuel, spokesman Steve Kraus said.

"The retirement of any one of these three units before construction of specified transmission upgrades in the area would result in violations of national reliability standards, unless an unacceptable amount of load were to be dropped in the Madison area," Jeffrey Webb, Midwest ISO director of expansion planning, said in the letter.

MG&E said it would retire the coal plant but now will burn natural gas instead of coal at the 90-megawatt coal portion of the Blount Street plant, spokesman Steve Kraus said. The rest of the plant already burns natural gas.

The announcement comes as American Transmission Co. and opponents of its proposed Dane County power line -- including the City of Madison -- prepare for public hearings next week. ATC has identified three possible routes for the project, projected to cost $214 million to $244 million.

In a recent report, state agencies analyzing the project said that the power line is still needed, despite the recesssion and declining sales of electricity. Consultants hired by several groups opposing the power line, including the City of Madison, say sagging power sales means the project isn't needed.

State regulators are expected to decide the fate of the Dane County project in June. ATC wants the project built by 2013.

About Thomas Content

Thomas Content covers energy, clean technology and sustainable business. A series he co-wrote on energy and climate change won top honors in 2008 from the National Press Foundation.

Energy Business News

EnSync Energy Systems has shipped a utility-scale energy storage system to South Korea, the Menomonee Falls company said.

The 500-kilowatt-hour system incorporates enough battery power for four or more hours of discharge, using EnSync’s zinc bromide flow batteries as well as power electronics and converters.

Formerly known as ZBB Energy, EnSync is focused on smaller energy storage systems for commercial buildings such as projects it's built in Hawaii in recent years. But it's also been working on larger energy storage systems.